Whether
male circumcision in infancy or childhood provides protection against the acquisition of human immunodeficiency virus (HIV) or other
sexually transmitted infections (
STIs) in adulthood remains to be established. In the first national cohort study to address this issue, we identified 810,719 non-Muslim males born in Denmark between 1977 and 2003 and followed them over the age span 0-36 years between 1977 and 2013. We obtained information about cohort members' non-therapeutic circumcisions, HIV diagnoses and other
STI outcomes from national health registers and used Cox proportional hazards regression analyses to calculate hazard ratios (HRs) with 95% confidence intervals (CIs) associated with foreskin status (i.e., circumcised v. genitally intact). During a mean of 22 years of follow-up, amounting to a total observation period of 17.7 million person-years, 3375 cohort members (0.42%) underwent non-therapeutic circumcision, and 8531 (1.05%) received hospital care for HIV or other
STIs. Compared with genitally intact males, rates among circumcised males were not statistically significantly reduced for any specific
STI. Indeed, circumcised males had a 53% higher rate of
STIs overall (HR = 1.53, 95% CI: 1.24-1.89), and rates were statistically significantly increased for anogenital
warts (74 cases in circumcised males v. 7151 cases in intact males, HR = 1.51; 95% CI: 1.20-1.90) and
syphilis (four cases in circumcised males v. 197 cases in intact males, HR = 3.32; 95% CI: 1.23-8.95). In this national cohort study spanning more than three decades of observation, non-therapeutic circumcision in infancy or childhood did not appear to provide protection against HIV or other
STIs in males up to the age of 36 years. Rather, non-therapeutic circumcision was associated with higher
STI rates overall, particularly for anogenital
warts and
syphilis.